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Numerical anatomy of lock-release gravity current

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Communications in Nonlinear Science and Numerical Simulation 2001年第4期6卷 183-192页

作者： Lizhu ZHANG, Yiran AN, Zhi LI, G. q. CHEN and Joseph H. W. LEE Department of mechanics and Engineering Science / State Key laboratory for Studies of Turbulence and Complex Systems, Peking University, Beijing 100871, China e-mail: zhlzh@*** De Dept. of mechanics and Eng. Science State Key Lab. Studs. T./C.S. Peking University Beijing 100871 China Department of Civil Engineering University of Hong Kong Hong Kong Hong Kong

Gravity currents created by releasing a fixed fluid into a less dense fluid are simulated numerically by using the renormalization group (RNG) k-ε. model for Reynolds-stress closure and a two-layer function as near wall treatment. A numerical anatomy of the gravity currents is made to characterize the concentration contour, velocity vector diagram, velocity profile, distribution of turbulent kinetic energy. streaklines and entrainment. Computed velocity structure of the current head explains why the front velocity decreases after the current advances about twelve lock lengths.

关键词： gravity current numerical simulation. environmental hydraulics

Nonlinear mechanics of a ring structure subjected to multi-pairs of evenly distributed equal radial forces

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Acta Mechanica Sinica 2017年第5期33卷 942-953页

作者： q. Chen F. Sun Z. Y. Li L. Taxis N. Pugno Biomechanics laboratory School of Biological Science and Medical Engineering Southeast University State Key laboratory of mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics School of Chemistry Physics and Mechanical EngineeringQueensland University of Technology (QUT) laboratory of Bio-Inspired and Graphene Nanomechanics Department of Civil Environmental and Mechanical Engineering University of Trento School of Engineering and Materials Science Queen Mary University of London Ket lab Italian Space Agency Via del Politecnico snc

Combining the elastica theory, finite element (FE) analysis, and a geometrical topological experiment, we studied the mechanical behavior of a ring subjected to multi-pairs of evenly distributed equal radial forces by looking at its seven distinct states. The results showed that the theoretical predictions of the ring deformation and strain energy matched the FE results very well, and that the ring deformations were comparable to the topological experiment. Moreover, no matter whether the ring was compressed or tensioned by N-pairs of forces, the ring always tended to be regular polygons with 2N sides as the force increased, and a proper compressive force deformed the ring into exquisite flower-like patterns. The present study solves a basic mechanical problem of a ring subjected to lateral forces, which can be useful for studying the relevant mechanical behavior of ring structures from the nano- to the macro-scale.

关键词： Ring structures Mechanical properties Shape Strain energy

Model Analysis of Fine Particle Pollution in Beijing during the 2008 Olympic Games

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Model Analysis of Fine Particle Pollution in Beijing during ...

Accuracy of LA-ICPMS zircon U-Pb age determination:An inter-laboratory comparison

第十届全国气溶胶会议暨第六届海峡两岸气溶胶技术研讨会

作者： Meigen Zhang 1 ,Lingyun Zhu 1 ,Yuesi Wang 1 ,Wenqing liu 2 1 State Key laboratory of Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029, China 2 Key lab.of environmental Optics and Technology,Anhui Institute of Optics and Fine mechanics,Chinese Academy of Sciences,Hefei 230031,China

Concentration distributions of major air pollutants over North China in the period of June-August 2008 were simulated by using a multi-scale air quality modeling system RAMS-CMAq,and for the evaluation of the model performance,model simulated concentrations of PM2.5,O3 and NOx were compared against observations obtained at 14 stations located in Beijing and its neighboring *** shows that modeled concentrations of PM2.5 and O3 agree with observed ones reasonably well, and the model captures major observed time-spatial variations,while large differences between modeled and simulated NOx values are found and the differences may be primarily due to coarse horizontal resolution of the model system as the model can not reflect the reality of the observation ***,the large differences are also associated with uncertainties in NOx emissions. Emission control was enforced in Beijing and its neighboring areas for the Beijing Olympic *** order to study the impacts of emission control upon PM2.5 and O3 concentrations,their concentrations were recalculated with the emissions without the emission control,and then discussed.

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Science China Earth Sciences 2015年第9期58卷 1722-1730页

作者： LI XianHua liu XiaoMing liu YongSheng SU Li SUN WeiDong HUANG Huiqing YI Keewook State Key laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences State Key laboratory of Continental Dynamics Department of Geology Northwest University State Key laboratory of Geological Processes and Mineral Resources Faculty of Earth Sciences China University of Geosciences Geological lab Center China University of GeosciencesBeijing State Key laboratory of Isotope Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences NSW Institute of Frontiers Geoscience School of Environmental and Life Sciences University of Newcastle University Drive Korea Basic Science Institute

LA-ICPMS zircon U-Pb dating has been greatly advanced and widely applied in the past decade because it is a cheap and fast *** internal error of LA-ICPMS zircon U-Pb dating can be better than 1%,but reproducibility(accuracy)is relatively *** order to quantitatively assess the accuracy of this technique,zircons from two dioritic rocks,a Mesozoic dioritic microgranular enclave(FS06)and a Neoproterozoic diorite(WC09-32),were dated independently in eight laboratories using SIMS and *** of three SIMS analyses on FS06 and WC09-2 are indistinguishable within error and give a best estimate of the crystallization age of 132.2 and 760.5 Ma(reproducibility is^1%,2RSD),*** U-Pb ages determined by LA-ICPMS in six laboratories vary from 128.3±1.0 to 135.0±0.9 Ma(2SE)for FS06 and from 742.9±3.1 to777.8±4.7 Ma(2SE)for WC09-32,suggesting a reproducibility of^4%(2RSD).Uncertainty produced during LA-ICPMS zircon U-Pb analyses comes from multiple sources,including uncertainty in the isotopic ratio measurements,uncertainty in the fractionation factor calculation using an external standard,uncertainty in the age determination as a result of common lead correction,age uncertainty of the external standards and uncertainty in the data *** of our study suggests that the uncertainty of LA-ICPMS zircon U-Pb dating is approximately 4%(2RSD).The uncertainty in age determination must be considered in order to interpret LA-ICPMS zircon U-Pb data rationally.

关键词： zircon U-Pb dating Laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) Secondary ion massspectrometry (SIMS) accuracy precision

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Vertical distributions of tropospheric SO_(2) based on MAX-DOAS observations: Investigating the impacts of regional transport at different heights in the boundary layer

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Journal of environmental Sciences 2021年第5期33卷 119-134页

作者： qianqian Hong Cheng liu qihou Hu Chengzhi Xing Wei Tan Ting liu Jianguo liu School of Environment and Civil Engineering Jiangnan UniversityWuxi214122China Center for Excellence in Regional Atmospheric Environment Institute of Urban EnvironmentChinese Academy of SciencesXiamen361021China Key lab.of environmental Optics&Technology Anhui Institute of Optics and Fine MechanicsHefei Institutes of Physical ScienceChinese Academy of SciencesHefei230031China Department of Precision Machinery and Precision Instrumentation University of Science and Technology of ChinaHefei230026China School of Earth and Space Sciences University of Science and Technology of ChinaHefei230026China Anhui Province Key laboratory of Polar Environment and Global Change University of Science and Technology of ChinaHefei230026China

Information on the vertical distribution of air pollutants is essential for understanding their spatiotemporal evolution underlying urban atmospheric environment. This paper presents the SO_(2) profiles based on ground-based Multi-Axis Differential Optical Absorption Spectroscopy(MAX-DOAS) measurements from March 2018 to February 2019 in Hefei, East China. SO_(2) decrease rapidly with increasing heights in the warm season, while lifted layers were observed in the cold season, indicating accumulation or long-range transport of SO_(2) in different seasons might occur at different heights. The diurnal variations of SO_(2) were roughly consistent for all four seasons, exhibiting the minimum at noon and higher values in the morning and late afternoon. Lifted layers of SO_(2) were observed in the morning for fall and winter, implying the accumulation or transport of SO_(2) in the morning mainly occurred at the top of the boundary layer. The bivariate polar plots showed that weighted SO_(2) concentrations in the lower altitude were weakly dependent on wind, but in the middle and upper altitudes, higher weighted SO_(2) concentrations were observed under conditions of middlehigh wind speed. Concentration weighted trajectory(CWT) analysis suggested that potential sources of SO_(2) in spring and summer were local and transported mainly occurred in the lower altitude from southern and eastern areas;while in fall and winter, SO_(2) concentrations were deeply affected by long-range transport from northwestern and northern polluted regions in the middle and upper altitudes. Our findings provide new insight into the impacts of regional transport at different heights in the boundary layer on SO_(2) pollution.

关键词： Sulfur dioxide MAX-DOAS Vertical distribution Regional transport

Study on strength properties and soil behaviour type classification of Huanghe River Delta silts based on variable rate piezocone penetration test

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Acta Oceanologica Sinica 2023年第11期42卷 146-158页

作者： Yunuo liu Guoqing Lin Yan Zhang Shenggui Deng Lei Guo Tao liu Shandong Provincial Key laboratory of Marine Environment and Geological Engineering Ocean University of ChinaQingdao 266100China College of environmental Science and Engineering Ocean University of ChinaQingdao 266100China Key lab.of Submarine Geosciences and Prospecting Techniques MOE China Ocean University of ChinaQingdao 266100China College of Marine Geosciences Ocean University of ChinaQingdao 266100China Institute of Marine Science and Technology Shandong UniversityQingdao 266237China qingdao National laboratory for Marine Science and Technology Qingdao 266100China

Fine-grained silt is widely distributed in the Huanghe River Delta(HRD)in China,and the sedimentary structure is complex,meaning that the clay content in the silt is *** piezocone penetration test(CPTu)is the most widely approved in situ test *** can be used to invert soil properties and interpret soil *** analyse the strength properties of surface sediments in the HRD,this paper evaluated the friction angle and its inversion formula through the CPTu penetration test and monotonic simple shear test and other soil unit *** evaluation showed that the empirical formula proposed by Kulhawy and Mayne had better prediction and inversion *** HRD silts with clay contents of 9.2%,21.4%and 30.3%were selected as samples for the CPTu variable rate penetration *** results show as follows.(1)The effects of the clay content on the tip resistance and the pore pressure of silt under different penetration rates were *** tip resistance q_t is strongly dependent on the clay content of the silt,the B_(q)value of the silt tends to 0 and is not significantly affected by the change of the CPTu penetration rate.(2)Five soil behavior type classification charts and three soil behavior type indexes based on CPTu data were *** results show that the soil behavior type classification chart based on soil behavior type index ISBT,the Robertson 2010 behavior type classification chart are more suitable for the silty soil in the HRD.

关键词： Huanghe River Delta piezocone penetration test silty soils clay content friction angle soil behaviour type classification

掺Er^（3＋）和掺Er^（3＋）／Yb^（3＋）光纤中1313nm到780nm的频率上转换过程

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中国激光 1996年第10期23卷 925-928页

作者：胡巍刘东峰陈国夫王贤华侯洵中国科学院西安光机所瞬态光学技术国家重点实验室

研究了在连续锁模和调Ｑ锁模两种脉冲泵浦条件下，掺Ｅｒ（３＋）和掺Ｅ３＋／Ｙｂ３＋单模ＧｅＯ２／ＳｉＯ２石英光纤中，１３１３ｎｍＮｄ：ＹＬＦ激光到７８０ｎｍ波长的频率上转换过程。Ｅｒ３＋离子在共振吸收两个光子后到４Ｆ９... 详细信息

研究了在连续锁模和调Ｑ锁模两种脉冲泵浦条件下，掺Ｅｒ（３＋）和掺Ｅ３＋／Ｙｂ３＋单模ＧｅＯ２／ＳｉＯ２石英光纤中，１３１３ｎｍＮｄ：ＹＬＦ激光到７８０ｎｍ波长的频率上转换过程。Ｅｒ３＋离子在共振吸收两个光子后到４Ｆ９／２态，再经快速的无辐射转移到４Ｉ９／２态．形成７８０ｎｍ辐射。在连续锁模泵浦条件下．１３１３ｎｍ至７８０ｎｍ的转换效率比调Ｑ锁模条件下更高．而后者的峰值功率是前者的几百倍。

关键词：光纤铒离子镱离子掺杂

Vertical distribution and temporal evolution of formaldehyde and glyoxal derived from MAX-DOAS observations:The indicative role of VOC sources

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Journal of environmental Sciences 2022年第12期34卷 92-104页

作者： qianqian Hong Cheng liu qihou Hu Yanli Zhang Chengzhi Xing Jinping Ou Wei Tan Haoran liu Xiaoqing Huang Zhenfeng Wu School of Environment and Civil Engineering Jiangnan UniversityWuxi 214122China Center for Excellence in Regional Atmospheric Environment Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China Key lab.of environmental Optics&Technology Anhui Institute of Optics and Fine MechanicsHefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China Department of Precision Machinery and Precision Instrumentation University of Science and Technology of ChinaHefei 230026China Anhui Province Key laboratory of Polar Environment and Global Change University of Science and Technology of ChinaHefei 230026China Guangdong Key laboratory of environmental Protection and Resources Utilization State Key Laboratory of Organic GeochemistryGuangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China Guangdong-Hongkong-Macao Joint laboratory of Collaborative Innovation for environmental quality Guangzhou 510632China Institute of Physical Science and Information Technology Anhui UniversityHefei 230601China

Formaldehyde(HCHO)and glyoxal(CHOCHO)are important oxidization intermediates of most volatile organic compounds(VOCs),but their vertical evolution in urban areas is not well *** profiles of HCHO,CHOCHO,and nitrogen dioxide(NO_(2))were retrieved from ground-based Multi-Axis Differential Optical Absorption Spectroscopy(MAXDOAS)observations in Hefei,*** and CHOCHO vertical profiles prefer to occur at higher altitudes compared to NO_(2),which might be caused by the photochemistry-oxidation of longer-lived VOCs at higher *** means of HCHO concentrations were higher in summer,while enhanced amounts of NO_(2)were mainly observed in *** exhibited a hump-like seasonal variation,with higher monthly-averaged values not only occurred in warm months(July-August)but also in cold months(November-December).Peak values mainly occurred during noon for HCHO but emerged in the morning for CHOCHO and NO_(2),suggesting that HCHO is stronger link to photochemistry than *** further use the glyoxal to formaldehyde ratio(GFR)to investigate the VOC sources at different *** lowest GFR value is almost found in the altitude from 0.2 to 0.4 km,and then rises rapidly as the altitude *** GFR results indicate that the largest contributor of the precursor VOC is biogenic VOCs at lower altitudes,while at higher altitudes is anthropogenic *** findings provide a lot more insight into VOC sources at vertical direction,but more verification is recommended to be done in the future.

关键词： Formaldehyde Glyoxal MAX-DOAS Vertical distribution VOC

Ground-Based Hyperspectral Stereoscopic Remote Sensing Network: A Promising Strategy to Learn Coordinated Control of O_(3) and PM_(2.5) over China

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Engineering 2022年第12期19卷 71-83页

作者： Cheng liu Chengzhi Xing qihou Hu qihua Li Haoran liu qianqian Hong Wei Tan Xiangguang Ji Hua Lin Chuan Lu Jinan Lin Hanyang liu Shaocong Wei Jian Chen Kunpeng Yang Shuntian Wang Ting liu Yujia Chen Department of Precision Machinery and Precision Instrumentation University of Science and Technology of ChinaHefei 230026China Center for Excellence in Regional Atmospheric Environment Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China Key lab.of environmental Optics and Technology Anhui Institute of Optics and Fine MechanicsHefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China Key laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes University of Science and Technology of ChinaHefei 230026China Anhui Province Key laboratory of Polar Environment and Global Change University of Science and Technology of ChinaHefei 230026China School of Earth and Space Sciences University of Science and Technology of ChinaHefei 230026China School of environmental Science and Optoelectronic Technology University of Science and Technology of ChinaHefei 230026China Institute of Physical Science and Information Technology Anhui UniversityHefei 230601China School of Environment and Civil Engineering Jiangnan UniversityWuxi 214122China

With the coming of the“14th Five-Year Plan,”the coordinated control of particulate matter with an aerodynamic diameter no greater than 2.5 lm(PM_(2.5))and O_(3) has become a major issue of air pollution prevention and control in *** stereoscopic monitoring of regional PM_(2.5) and O_(3) and their precursors is crucial to achieve coordinated ***,current monitoring networks are currently inadequate for monitoring the vertical profiles of both PM_(2.5) and O_(3) simultaneously and support air quality *** University of Science and Technology of China(USTC)has established a nationwide ground-based hyperspectral stereoscopic remote sensing network based on multi-axis differential optical absorption spectroscopy(MAX-DOAS)since *** monitoring network provides a significant opportunity for the regional coordinated control of PM_(2.5) and O_(3) in ***-year vertical profiles of aerosol,NO_(2) and HCHO monitored from four MAX-DOAS stations installed in four megacities(Beijing,Shanghai,Shenzhen,and Chongqing)were used to characterize their vertical distribution differences in four key regions,Jing–Jin–Ji(JJJ),Yangtze River Delta(YRD),Pearl River Delta(PRD),and Sichuan Basin(SB),*** normalized and yearly averaged aerosol vertical profiles below 400 m in JJJ and PRD exhibit a box shape and a Gaussian shape,respectively,and both show exponential shapes in YRD and *** NO_(2) vertical profiles in four regions all exhibit exponential shapes because of vehicle *** shape of the HCHO vertical profile in JJJ and PRD was Gaussian,whereas an exponential shape was shown in YRD and ***,a regional transport event occurred at an altitude of 600–1000 m was monitored in the southwest–northeast pathway of the North China Plain(NCP)by five MAX-DOAS stations(Shijiazhuang(SJZ),Wangdu(WD),Nancheng(NC),Chinese Academy of Meteorological Sciences(CAMS),and University of Chinese Academy of Sciences(UCAS))belonging to the above network

关键词： MAX-DOAS Stereoscopic monitoring Regional transport Ozone production Control strategy